Sad Face : (...I like them as a couple!

On July 7, Michael Jackson’s family ­gathered to celebrate him at his much-watched memorial service.

Noticeably absent?

Janet ­Jackson’s longtime music-exec boyfriend, Jermaine Dupri. (A pal says Dupri skipped the memorial because he “doesn’t attend funerals.”)

And for good reason. “His friends are telling people it’s over,” a source tells the new issue of Us Weekly, on stands now.

Echoes another: “They have been moving in different directions for a while.”

So what drove Jackson, 43, and Dupri, 36, apart after nearly seven years?

“You shouldn’t mix business with pleasure,” a mutual pal explains. (Dupri produced several tracks on her last two CDs.) “Janet felt their lives were too crossed and they should have kept things sepa­rate.”

See who else is single this summer.

Plus, the polar opposites were never too compatible.

“Jermaine likes to be out there, mingling with everybody, and ­Janet’s more shy.” (And secretive: She kept her nine-year marriage to Rene Elizondo hidden until their 2000 ­divorce.)

Meanwhile, Jackson is still deeply mourning the death of her big brother.

“She’s devastated,” an insider says. “She’s busy caring for Michael’s kids. Janet’s the family’s backbone.”

See photos of Jackson and his kids through the years.

Jackson’s rep couldn’t be reached.